I doubt that PostgreSQL has substantially more disk overhead
than other DBMS with comparable capabilities (comparison with
flat files or MyISAM would be unfair).
You're right, of course; the same data on InnoDB works out if anything slightly larger, as far as I can tell.
I wasn't (and I'm not) trying to do-down pgsql, just trying to figure out if there's a way of cutting back on the extra space used. In this instance it would be nice to be able to mark a table as WORM, for example, and remove the need for any of this stuff. At least in MySQL I can specify MyISAM for the table, since it rarely if ever needs updates and so there's no requirement for MVCC.
Have you tried using pg_filedump
(http://pgfoundry.org/frs/?group_id=1000541)
to dump a page or two of your table and figure
out what is where and where the space went?
I haven't; I will do for interest's sake, thanks for the suggestion.
Geoff
